It is common in the construction industry to manufacture concrete slabs of various sizes offsite from a construction site. After manufacturing concrete slabs offsite, the concrete slabs must be transferred to the construction site. To transfer the concrete slabs to the construction site, the concrete slabs are typically lifted onto the bed of a truck, transported to the construction site, lifted off of the bed of the truck, and moved to the correct location at the construction site. Since each concrete slab typically weighs several tons, multiple lifting apparatuses are typically used to assist in lifting each concrete slab.
One such known lifting apparatus used to assist in lifting a concrete slab includes a known embedded lifting base and a known threaded lifting insert. The embedded lifting base is configured to be embedded in the concrete slab when the concrete slab is manufactured. This known embedded lifting base includes an internally threaded vertically extending channel having an upper opening. Four spaced apart lifting bases are typically embedded in a manufactured concrete slab (i.e., an embedded lifting base is embedded in each quarter of the concrete slab).
This known threaded lifting insert includes a stem. The stem includes threads that are configured to threadably engage the threads of the internally threaded channel of the embedded lifting base. In operation, a separate lifting insert is threadably inserted into each embedded lifting base in the concrete slab. When the lifting inserts are properly secured in the embedded lifting bases, hooking members attached to a lifting machine (such as a crane) are attached to each lifting insert to enable the lifting machine to lift and move the concrete slab to the proper location, such as onto or off of the bed of a truck.
One problem associated with this known lifting apparatus is that installing and removing the lifting inserts from each embedded lifting base is a time-consuming and a laborious process. This is a time-consuming process since the length of the threaded stem of the lifting insert is almost equal to the thickness of the concrete slab. Inserting and removing the lifting inserts from each lifting base is especially laborious and time-consuming when many concrete slabs must be moved.
This known lifting apparatus is also configured to be used to adjust the height of concrete paving slabs on the sub-grade so that the top surface of the concrete paving slab is level with adjacent top surfaces of adjacent concrete paving slabs or pavement surfaces.
More specifically, this known embedded lifting base includes a lifting plate. The lifting plate is set into the underneath portion of the concrete slab. To adjust the height of the concrete slab, a threaded jacking rod is inserted into the internally threaded channel of the embedded lifting base. The jacking rod engages and forces the lifting plate downwardly to adjust the height of the concrete slab.
Inserting the jacking rod in the internally threaded channel of the embedded lifting base is also a time-consuming and laborious process for similar reasons as for the lifting inserts described above. Additionally, once jacking and grouting of the concrete pavement slab is completed, the jacking rod must be removed which is also time-consuming and laborious and delays the finalization of the pavement repair process.
Accordingly, an improved lifting and jacking apparatus is needed.